The specific aims of this predoctoral thesis research is to estimate the association between stages of drug use (i.e., nicotine, alcohol, marijuana and cocaine) and suicide ideation and attempts, within the context of a longitudinal study of young adults who originally were recruited and assessed as an epidemiological sample. The conceptual framework is oriented by the life-span developmental concepts of Kellam and Ensminger (1980), with elaboration of social context of the type espoused by Szapocznik and Coatsworth (1999). These specific aims will be studied with a prospective research design that involved repeated annual assessments of the 2,311 participating youths between their entry to first grade and age 14 years. They are now being followed up as young adults, with standardized assessments of drug disorders, suicide ideation and attempts, as well as possible mediators, e.g. depression and aggression. Statistical models used to estimate the associations will include GLM with a logistic link, survival analysis, latent trait models, and latent transition models. A power analysis is included as part of the proposal, as well as an overview of alternative procedures, weaknesses and counterbalancing strengths.